This invention relates generally to the delivery and use of polyacid/polyether complexes, cross-linked gels comprising polyacids, polyalkylene oxides and multivalent ions, the formation and delivery of foams and gels to inhibit the formation of adhesions between tissues and to promote hemostasis.
Adhesions are unwanted tissue growths occurring between layers of adjacent bodily tissue or between tissues and internal organs. Adhesions commonly form during the healing which follows surgical procedures, and when present, adhesions can prevent the normal motions of those tissues and organs with respect to their neighboring structures.
The medical and scientific communities have studied ways of reducing the formation of post-surgical adhesions by the use of high molecular weight carboxyl-containing biopolymers. These biopolymers can form hydrated gels which act as physical barriers to separate tissues from each other during healing, so that adhesions between normally adjacent structures do not form. After healing is substantially complete, the barrier is no longer needed, and should be eliminated from the body to permit more normal function of the affected tissues.
Schwartz et al (U.S. Pat. Nos. 5,906,997, 6,017,301, and 6,034,140) describe membranes, hydrogels and association complexes of carboxypolysaccharides and polyethers for use as antiadhesion compositions. Because of the presence of polyethers in membranes made using these materials, these compositions exhibited certain antithrombogenic properties, including decreased platelet adhesion, decreased platelet activation, and decreased binding of fibrin and blood clots to membranes. U.S. patent application Ser. No.: 09/472,110, incorporated herein fully by reference, disclosed that multivalent cations including Fe3+, Al3+, and Ca2+, and/or polycations including polylysine and polyarginine can be used to provide intermolecular attraction, thereby providing a means of controlling viscoelastic properties of gels.
Davies et al. (U.S. Pat. No.: 5,169,037 and RE35,540) describe pressurized canisters having a product bag therein.
Stoffel (U.S. Pat. No. 5,126,086) describes a pressurized container having an inner bag for delivery of product.
Obrist (U.S. Pat. No. 5,799,469) describes a method of manufacture and a pressure pack having an outer container and a bag for holding the product to be dispensed.
Patterson (U.S. Pat. No. 4,350, 272) describes a barrier package having a controlled release coating that can peel from the package and form a barrier between the product and propellant.
Prior art delivery systems are depicted in FIGS. 1 and 2. FIG. 1 depicts a delivery system having a canister 100, comprising a top 103 and a bottom 118, having a bag 102 therein, to contain the product to be delivered. The bag is sealed with gusset 105, and has valve mechanism 117 with an actuator 101. The top 106 of bag 102 is shown suspended from the valve mechanism 117.
FIG. 2 depicts a prior art delivery system similar to that shown in FIG. 1, but additionally having a delivery tube 120.
There is need for improved antiadhesion products, including foams, that can be used quickly and efficiently by surgeons so as to achieve desired clinical results.
In certain aspects, this invention comprises new antiadhesion foams and methods and devices for delivering antiadhesion gels, sprays or foams. The antiadhesion product to be delivered is placed in a canister under pressure, and when a valve is opened, the product exits the canister and can be delivered to a surgical site. In embodiments in which the antiadhesion composition is in direct contact with a propellant gas, when delivered, the composition can be in the form of a foam. In embodiments in which the antiadhesion composition is separated from the propellant gas, the composition can be delivered as a gel or a spray.
In other embodiments, a gas capsule is mounted within the canister to increase the amount of antiadhesion product delivered. A gas capsule is an additional pressure storage chamber within a first pressure storage chamber that is used for propellant. As the pressure in the first storage chamber becomes depleted as the propellant is discharged, the gas capsule can provide additional propellant to expel more of the product from the canister. A gas capsule can be used in any situation, not limited to delivery of antiadhesion compositions, in which it is desirable to deliver more of the contents of the canister than can be delivered using a simple single-compartment pressure system. In certain of these embodiments, the gas capsule can be charged prior to insertion within the canister. In other embodiments, the gas capsule can be charged while inside the canister. Upon charging, the gas capsule can be pressurized to the same degree as the canister. In certain embodiments, the gas capsule can be adapted to open only when the pressure within the gas capsule compared to the canister pressure exceeds a desired threshold. Thus, when a portion of the antiadhesion product has been delivered and the pressure within the canister is reduced, the higher pressure within the secondary source can open a valve and transiently increase the pressure in the canister to permit additional product to be expelled from the canister.
The types of antiadhesion compositions is not limited by the delivery system. Any antiadhesion composition can be delivered if the physical properties of the composition are compatible with pressure delivery. In one aspect of the invention, a composition can be desirable that comprises a foam of an intermacromolecular association of a polyacid (xe2x80x9cPAxe2x80x9d) such as a carboxypolysaccharide (CPS) and a polyalkylene oxide (xe2x80x9cPOxe2x80x9d) such as a polyether (PE), for example, a polyethylene oxide (xe2x80x9cPEOxe2x80x9d). Antiadhesion compositions based on association complexation between ionically associated or hydrogen bonded polyacids (xe2x80x9cPAxe2x80x9d) and hydrophilic polyalkylene oxides (xe2x80x9cPOxe2x80x9d) can have different hemostatic, antiadhesion, and other physiological properties depending upon the pH, the PO and the PA contents, the total solids content, as well as other properties of the composition. As described further below, the PA of this invention can be made with polyacrylic acid, carboxypolysaccharides such as CMC, and other polyacids known in the art. Ionically cross-linked gels of this invention can be made by mixing polyacid and polyether together, either in dry form or in aqueous solution, and then adding a solution containing cations to provide cross-linking between the PA, the PO and the cations. The pH of the composition can be adjusted. The gels can then be sterilized and stored before use.
The compositions of this invention can be used to inhibit post-surgical adhesions, to decrease the consequences of arthritis, and/or to provide a lubricant for numerous medical and/or veterinary uses. The gels and foams of this invention can be used in conjunction with antiadhesion membranes to provide rapidly acting hemostatic effects, and longer-lasting antiadhesion properties. These properties of antiadhesion compositions can improve wound healing from traumatic injuries and/or surgeries.
Additionally, in accordance with some aspects of the invention, drugs can be included in the membranes or gels to deliver pharmacological compounds directly to the tissues. Certain of these embodiments can include the use of thrombin or other hemostatic agents to further inhibit bleeding at a surgical or wound site.
In certain embodiments, the compositions can be sterilized using thermal methods, gamma irradiation, ethylene oxide, and ion beams which can alter the physical and other properties of the components. Alternatively, in other embodiments of this invention, the materials can be filter sterilized. The materials are biocompatible, and can be cleared from the body within a desired period of time, thereby reducing chronic adverse effects.